This invention relates to the field of hydraulic presses and improvements relating thereto.
The hydraulic press has long been a useful tool in industry for performing various pressing operations such as blanking, stamping, and drawing. The basic design of the typical hydraulic press comprises a motor for driving a hydraulic pump so that such pump delivers a suitable hydraulic fluid, such as oil, to alternate sides of a piston at corresponding downstroke and upstroke positions of a reciprocation cycle (hereafter sometimes denoted as simply a "stroke"). The piston, as slidably received in a cylinder, is connected to a ram member (such as simply a plate, or a suitably shaped die for stamping or blanking) which contacts a workpiece upon the downstroke of the ram member.
Although prior art hydraulic presses have long been successfully used in industry, it would be desirable to provide improvement(s) which would decrease the horsepower requirements of the motor to achieve a desired force upon the workpiece (hereafter referred to as "tonnage", or the number of tons exerted upon the workpiece by the ram member), while at the same time permitting operation of the press at different reciprocation speeds(i.e. in strokes per minute or s.p.m.) at a constant desired tonnage.